An optical coherent tomography imaging apparatus for diagnosis (OCT) (for example, see Japanese unexamined patent publication No. 2001-79007) or an optical frequency domain imaging (OFDI) apparatus utilizing wavelength sweep, which is an improved type of OCT, are widely utilized for diagnosis before an operation through treatment inside a blood vessel with a high functional catheter such as a balloon catheter, a stent or the like, or for a result confirmation after an operation (hereinafter, in this disclosure, the optical coherent tomography imaging apparatus for diagnosis (OCT) and the optical frequency domain imaging (OFDI) apparatus utilizing wavelength sweep will be generically referred to as “optical imaging apparatus for diagnosis”).
In the aforementioned optical imaging apparatus for diagnosis, an optical probe unit includes an imaging core equipped with an optical lens or optical mirror (transmitting and receiving unit) attached at the distal end of an optical fiber cable. The optical probe unit is inserted inside a blood vessel and, while rotating the imaging core, a measurement light is emanated from the transmitting and receiving unit at the distal end into the blood vessel and concurrently, a radial scan inside the blood vessel is carried out for light-receiving reflected light from the biological tissue. Then, after generating interference light by making the aforementioned light-received reflected-light and reference light interfere with each other, a cross-sectional image of the blood vessel is visualized based on the aforementioned interference light.
For the radial scan of the imaging core, the scan is carried out generally by using a rotational drive unit referred to as a scanner and pull-back unit and the optical probe unit is detachably attached to the aforementioned rotational drive unit.
When performing measurements, it is necessary to protect the scanner and pull-back unit from liquid such as blood or the like. That is, problems may occur in the rotation drive when a liquid such as blood or the like gets into the scanner and pull-back unit at the time of measurement. Also, in a case in which the inside of the scanner and pull-back unit is contaminated, there is concern that intensity of the optical signal (measurement light or reflected light) may attenuate (optical loss may occur) and an erroneous diagnosis is induced caused by the fact that the image quality of the visualized cross-sectional image deteriorates.